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Answered

LrC stuck syncing 192 files with empty error logs – Should I use "Rebuild Sync Data"?

Forum|Forum|4 days ago
September 21, 2026
6 replies
44 views

Since yesterday, I have been experiencing immense problems with the synchronization mechanism in Lightroom Classic. I created a collection containing 52 photos and marked it as synced.

After a while, I clicked on the synchronization history and saw that 192 images were being synchronized and this number was not changing. I then checked the "Sync Activity" section via the gear icon, and nothing was displayed there. After waiting for some time, the number 192 still hadn't changed.

Then, while in the sync activity window, I held down the Option Key, which reveals 3 buttons. I clicked the button for the diagnostic report and looked at the HTML log. Initially, I noticed that an old image file (which has nothing to do with the 52 new photos) appeared a total of 47 times. Since it was an old file that no longer needs to be synced, I turned off synchronization for that collection. However, this did not change the number 192.

In the meantime, I generated the diagnostic file again to check it more closely. Interestingly, the relevant sections 1a and 1b ("Syncing and Error Assets", and "Sync Pending Downloads") are completely empty. Therefore, even the log file gives me zero clues as to what might be causing the hang-up.

Otherwise, I couldn't see any entries. Clicking "View Sync Status on the Web" didn't help either; there I only see an empty sync error collection, and Lightroom Classic isn't showing any sync errors either.

The new collection itself appears in the cloud, but remains empty. Consequently, I also turned off synchronization for this collection again and manually removed the images from the "All Synced Photographs" collection. This didn't change anything either—it still claims that 192 images are being synced.

I have been on version 15.4.1 and made the update on version 15.5, but it didn#t help either.

What should I do now? Does it make sense to click the third button in the preferences window under sync activity titled "Rebuild Sync Data"?

BR, Thomas

Correct answer photopoeth

Update: Problem solved (but what a painful journey...)

I managed to fix the issue, but it was quite arduous and is realistically unfeasible for an average user. Here is how it played out, in case anyone else runs into this:

After renaming the sync.lrdata file (keeping a backup just in case) and restarting Lightroom Classic, the synchronization kicked off. The number of images to be synced temporarily spiked to over 5,000, which gave me quite a scare!

After a while, most of them cleared, but 10 images remained stuck and wouldn't go to zero. Just like before, the sync activity window via the gear icon showed an empty list, which was completely unhelpful.

However, because I had reset the cache (sync.lrdata), I decided to generate a new diagnostic log. And lo and behold: this time, Section 1a ("Syncing and Error Assets") actually contained those 10 entries!

Armed with that information, I was able to manually remove those specific files from the synchronization process, and finally—success! The green checkmark appeared on the cloud icon.

My final verdict / Feedback:
What really frustrates me is Adobe's failure to provide proper troubleshooting tools and guidance for its users. Having to dig into hidden diagnostic HTML logs and rename cache files via the operating system's file explorer is simply not practical for average users. If you don't have a bit of a technical background, you stand almost zero chance of solving a bug like this. Adobe really needs to do better here.

Thanks to @CORCTON34033231 for chiming in!

photopoethAuthor

Inspiring

Sorry for the triple postings. Something went awfully wrong and it seems I cannot delete the duplicate posts.

photopoethAuthorCorrect answer

Inspiring

Update: Problem solved (but what a painful journey...)

I managed to fix the issue, but it was quite arduous and is realistically unfeasible for an average user. Here is how it played out, in case anyone else runs into this:

After renaming the sync.lrdata file (keeping a backup just in case) and restarting Lightroom Classic, the synchronization kicked off. The number of images to be synced temporarily spiked to over 5,000, which gave me quite a scare!

After a while, most of them cleared, but 10 images remained stuck and wouldn't go to zero. Just like before, the sync activity window via the gear icon showed an empty list, which was completely unhelpful.

However, because I had reset the cache (sync.lrdata), I decided to generate a new diagnostic log. And lo and behold: this time, Section 1a ("Syncing and Error Assets") actually contained those 10 entries!

Armed with that information, I was able to manually remove those specific files from the synchronization process, and finally—success! The green checkmark appeared on the cloud icon.

My final verdict / Feedback:
What really frustrates me is Adobe's failure to provide proper troubleshooting tools and guidance for its users. Having to dig into hidden diagnostic HTML logs and rename cache files via the operating system's file explorer is simply not practical for average users. If you don't have a bit of a technical background, you stand almost zero chance of solving a bug like this. Adobe really needs to do better here.

Thanks to @CORCTON34033231 for chiming in!

photopoethAuthor

Inspiring

Update: Problem solved (but what a painful journey...)

I managed to fix the issue, but it was quite arduous and is realistically unfeasible for an average user. Here is how it played out, in case anyone else runs into this:

After renaming the sync.lrdata file (keeping a backup just in case) and restarting Lightroom Classic, the synchronization kicked off. The number of images to be synced temporarily spiked to over 5,000, which gave me quite a scare!

After a while, most of them cleared, but 10 images remained stuck and wouldn't go to zero. Just like before, the sync activity window via the gear icon showed an empty list, which was completely unhelpful.

However, because I had reset the cache (sync.lrdata), I decided to generate a new diagnostic log. And lo and behold: this time, Section 1a ("Syncing and Error Assets") actually contained those 10 entries!

Armed with that information, I was able to manually remove those specific files from the synchronization process, and finally—success! The green checkmark appeared on the cloud icon.

My final verdict / Feedback:
What really frustrates me is Adobe's failure to provide proper troubleshooting tools and guidance for its users. Having to dig into hidden diagnostic HTML logs and rename cache files via the operating system's file explorer is simply not practical for average users. If you don't have a bit of a technical background, you stand almost zero chance of solving a bug like this. Adobe really needs to do better here.

Thanks to @CORCTON34033231 for chiming in!

photopoethAuthor

Inspiring

Update: Problem solved (but what a painful journey...)

I managed to fix the issue, but it was quite arduous and is realistically unfeasible for an average user. Here is how it played out, in case anyone else runs into this:

After renaming the sync.lrdata file (keeping a backup just in case) and restarting Lightroom Classic, the synchronization kicked off. The number of images to be synced temporarily spiked to over 5,000, which gave me quite a scare!

After a while, most of them cleared, but 10 images remained stuck and wouldn't go to zero. Just like before, the sync activity window via the gear icon showed an empty list, which was completely unhelpful.

However, because I had reset the cache (sync.lrdata), I decided to generate a new diagnostic log. And lo and behold: this time, Section 1a ("Syncing and Error Assets") actually contained those 10 entries!

Armed with that information, I was able to manually remove those specific files from the synchronization process, and finally—success! The green checkmark appeared on the cloud icon.

My final verdict / Feedback:
What really frustrates me is Adobe's failure to provide proper troubleshooting tools and guidance for its users. Having to dig into hidden diagnostic HTML logs and rename cache files via the operating system's file explorer is simply not practical for average users. If you don't have a bit of a technical background, you stand almost zero chance of solving a bug like this. Adobe definitely needs to do better here!

Thanks to @CORCTON34033231 for chiming in!

CORCTON34033231

Community Expert

I wouldn't — Adobe specifically warns against using Rebuild Sync Data unless the Adobe team directs it. See the official sync FAQ: https://helpx.adobe.com/lightroom-classic/desktop/technical-support/workflow-issues/sync-issues/sync-faq.html

You've already done the right checks (sync activity, web sync status, error collection). Since nothing shows on either side, the next step is to contact Adobe support with your diagnostic report — they can see the stuck assets on their end.

photopoethAuthor

Inspiring

The FAQ doesn’t help a lot. As you can see in my answer, solving the issue wa a bit nerdy...

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